1. Field of the Invention
The present invention relates to a vehicle traveling test apparatus, such as a chassis dynamometer, configured to cause a wheel of a vehicle such as a car to rotate in a state where a frame of the vehicle is kept still and to carry out various tests for the car.
2. Related Art
Recently, instead of letting a car travel on a test course, a traveling test apparatus by which various measurements are carried out by driving the car in a room is being utilized. In the traveling test apparatus, a drive wheel of the car is caused to contact a drum or an endless belt, and a body of the car is kept still even though the drive wheel rotates. By the above traveling test apparatus, there are performed various tests such as measurement of vibration of the car body and/or noises inside the car generated while the car is traveling, measurement of gas emission, and a test of an effect of a steering wheel. In such a test apparatus, a belt-type apparatus that causes a tire to contact a plane is preferred rather than a drum-type apparatus that causes the tire to contact a curved surface. There is cited as such a traveling test apparatus a chassis dynamometer disclosed in Japanese Patent Provisional Publication No. HEI 6-207886. The chassis dynamometer reproduces various traveling conditions by applying a load to a drum or an endless belt rotated in conjunction with a drive wheel while the drive wheel is rotating (it is referred to as drive absorption). In such a chassis dynamometer, a motor for the drive absorption is prepared outside the chassis dynamometer.
There is included in such a chassis dynamometer a chassis dynamometer configured with a load sensor provided at a bearing that supports a rotating member such as a pair of rollers around which the endless belt is hung and the drum so as to measure variation of a load transmitted from the drive wheel of the car to the drum or the endless belt. Thus, by the load sensor being provided to the chassis dynamometer, it is possible to evaluate the vibration of the car and the noises inside the car without attaching any sensor to the car.
Additionally, in such a belt-type traveling test apparatus, when there is caused unconformity between a circumferential direction of the tire and a traveling direction of the endless belt, a lateral force is applied to the belt. When the lateral force exceeds a predetermined value, the endless belt is laterally shifted from the pair of rollers. Since the shift of the belt might cause drop-off and/or fracture of the endless belt, it is desired to avoid the shift as much as possible.
In a configuration of the traveling test apparatus disclosed in Japanese Patent Provisional Publication No. HEI 6-207886, rotation shafts of the pair of rollers around which the endless belt is hung can be tilted, and when the shift of the endless belt is detected, the shift is recovered by tilting the rotation shafts such that the endless belt moves in an opposite direction of a direction in which the endless belt has shifted.